The invention relates to a cylinder head for multi-cylinder internal combustion engine, and more particularly, to a cylinder head with a cylinder head block bounding a cooling water space, and closed at the top by a cylinder head cover plate. The block has tubular chambers extending in the direction of the cylinder axis to accommodate a spark plug and injection nozzle or an injection nozzle with precombustion chamber. A camshaft space is located above the cover plate with devices for valve control. A bearing pedestal to accommodate at least one camshaft and separate from the cylinder head block is provided in the camshaft space, and the bearing locations for the camshaft are covered by bearing covers.
DE-PS 39 40 845 shows a cylinder head consisting of a cylinder head block and, placed thereon, a bearing pedestal for accommodating camshafts and the associated bearing covers. The bearing pedestal is carried on a flange formed by the side and end walls of the cylinder head block and on a support column located between the individual cylinder sections in the central longitudinal plane of the cylinder head. The flange formed by the upper termination of the side and end walls simultaneously acts as the support for a rocker cover which closes off the camshaft space. A tubular chamber extending in the direction of the cylinder axis is provided in the cylinder head block to accommodate a spark plug or an injection nozzle which emerges into the camshaft space above the cylinder head cover plate.
A disadvantage of the configuration of the split plane between the cylinder head block and the bearing pedestal at the level of the upper termination of the cylinder head side walls and cylinder head end walls above the termination of the tubular chamber is that, during the manufacture of the cylinder head block, the surfaces of the split plane and the termination of the chamber have to be machined in separate operations. This fact lengthens the machining time and makes manufacture more expensive.
A further disadvantage in the known cylinder head arrangement resides in the fact that, because the bearing pedestal is carried on the side and end walls, the walls extending between the bearing pedestal and the cylinder head cover are excited to vibration and therefore increase the noise radiated from the internal combustion engine.
An object of the present invention is, therefore, to provide a cylinder head which reduces the manufacturing requirements. A further object of the present invention is to minimize the noise radiation caused by the cylinder head side walls.
These objects have been achieved in accordance with the present invention, by forming a split plane between the cylinder head block and the bearing pedestal, with the split plane extending at the level of the upper edge of the chamber.
On the basis of the known cylinder head for a multi-cylinder internal combustion engine with tubular chambers extending in the direction of the cylinder axis in the cylinder head block, the bearing pedestal located in the camshaft space above the cover plate of the cylinder head block is placed, according to the present invention, such that the split plane between the cylinder head block and the bearing pedestal extends at the level of the upper edge of the tubular chamber. This ensures that all the support surfaces on the bottom of the bearing pedestal and all the corresponding support surfaces in the cylinder head block are located in one plane and can therefore be machined in one operation. Reclamping of the parts or movement of the tool into a different plane becomes unnecessary. The manufacturing requirements are thus reduced and the machining time shortened. Because of the movement of the split plane, as described, vibrations caused by the cam drive are introduced directly into the cylinder head block and no longer via the cylinder head end walls and cylinder head side walls. The noise radiation emerging from these walls is reduced.
In one currently preferred embodiment of the present invention, the cylinder head end walls and cylinder head side walls extend beyond the above-mentioned split plane as far as a plane underneath the split plane formed between the bearing pedestal and the bearing covers. Because the bearing cover split plane is located above the side walls, machining of the bearing bores for the camshafts can be undertaken with the bearing pedestal fitted.